It is desirable for a number of purposes to locate two or more laterally displaced compositions in a highly interdigitated relationship on a support. In those instances where the compositions are divided into very small individual areas (e.g., microareas--here defined as areas too small to be readily individually resolved by the unaided human eye), the techniques for locating the compositions in a predetermined laterally displaced relationship have been both tedious and complex.
A specific illustrative application for highly interdigitated compositions is additive multicolor photography. In additive multicolor photography a multicolor filter is employed which can be comprised of three additive primary filters that are segmented and interlaid to form the smallest attainable discrete areas. By exposing through the multicolor filter a panchromatically responsive imaging material--such as a panchromatically sensitized silver halide emulsion--it is possible to form a multicolor image. For instance, a negative-working silver halide emulsion can produce a multicolor negative image following exposure and development when exposed and viewed through the multicolor filter. A directpositive imaging material will similarly produce a positive multicolor image. This approach, commercialized under the name Dufaycolor, and variations of it are illustrated by Dufay U.K. Pat. No. 15,027 (1912), Dufay U.S. Pat. No. 1,003,720, Land U.S. Pat. No. 3,138,459, and James, The Theory of the Photographic Process, 4th Ed., Macmillan, 1977, p. 335.
Dufay and others recognized the desirability of providing segmented interlaid filters of the smallest attainable sizes. Disadvantages were encountered in achieving proper registration of filter segments. Lateral spreading of the materials forming the filter segments was recognized to pose limitations, since unwanted mixing of filter materials, even if confined to edge regions, can produce unwanted shifts in hue. Dufay and others generally employed planar support surfaces, but in some instances filter segments were located in grooves.
K. E. Whitmore U.S. Pat. No. 4,363,806 recognized that lateral spreading can be overcome by placing the filter materials to microcells (or microvessels).
Whitmore applies to photographic imaging the use of supports containing arrays of microcells opening toward one major surface. In a variety of different forms the photographic elements and components disclosed by whitmore contain an array of microcells in which first, second, and, usually, third sets of identical microcells are interspersed to form an interlaid pattern. In a typical form three separate sets of microcells, each containing a different subtractive primary (i.e., yellow, magenta, or cyan) or additive primary (i.e., blue, green, or red) imaging component, are interlaid. Preferably each microcell of each set is positioned laterally next adjacent at least one microcell of each of the two remaining sets. The microcells are intentionally sized so that they are not readily individually resolved by the human eye, and the interlaid relationship of the microcell sets further aids the eye in fusing the imaging components of the separate sets of microcells into a multicolor image.
In one specifically preferred embodiment disclosed by Whitmore, cyan, magneta, and yellow dyes or dye precursors of alterable mobility are associated with immobile red, green, and blue colorants, respectively, each present in one of the first, second, and third sets of microcells, and the microcells are overcoated with a panchromatically sensitized silver halide emulsion layer. By exposing the silver halide emulsion layer through the microcells and then developing, an additive primary multicolor negative image can be formed by the microcellular array and the silver halide emulsion layer while cyan, magneta, and yellow dyes can be transferred to a receiver in an inverse relationship to imagewise exposure to form a subtractive primary positive multicolor image. The foregoing is merely exemplary, many other embodiments being disclosed by Whitmore.
A technique disclosed by Whitmore for differentially filling microcells to form an interlaid pattern calls for first filling the microcells of an array with a sublimable material. The individual microcells forming a first set within the array can then be individually addressed with a laser to sublime the material initially occupying the first set of microcells. The emptied microcells can then be filled by any convenient conventional technique with a first imaging component. The process is repeated acting on a second, interlaid set of microcells and filling the second set of emptied microcells with a second imaging component. The process can be repeated again where a third set of interlaid microcells it to be filled, although individual addressing of microcells is not in this instance required. This approach is suggested by Whitmore to be useful in individually placing triads of additive and/or subtractive primary materials in first, second, and third sets of microcells, respectively.
H. S. A. Gilmour U.S. Ser. No. 192,976, filed Oct. 1, 1980, commonly assigned, titled AN IMPROVEMENT IN THE FABRICATION OF ARRAYS CONTAINING INTERLAID PATTERNS OF MICROCELLS, now abandoned in favor of U.S. Ser. No. 375,423, filed May 6, 1982, now U.S. Pat. No. 4,386,145, improves on Whitmore's process of filling interlaid sets of microcells with differing imaging compositions by employing a thermally destructible membrane to close one set of microcells while another set is being filled with or emptied of imaging material.
R. N. Blazey et al U.S. Pat. No. 4,307,165 improves on the processes of Whitmore and Gilmour in eliminating the need to employ either a sublimable material or a destructible membrane. Blazey et al differentially electrostically charges differing sets of microcells and employs an electrographic imaging composition to fill selectively at least a first set of microcells. In a preferred form the microcells are formed in an organic photoconductor, the photoconductor is electrostatically charged in a nonimagewise manner, laser scanning is employed to dissipate the electrostatic charge from a first set of microcells, electrographic development introduces a first imaging composition into the first set of microcells, and the process is twice repeated to fill second and third sets of microcells with second and third imaging compositions.
Land U.S. Pat. No. 3,284,208 illustrates the formation of a multicolor filter array for additive primary imaging using a transparent lenticular support. The lenticules on one major surface of the support are used to focus radiation in discrete areas on the opposite surface of the support bearing a radiation-sensitive material. By removing unexposed radiation-sensitive material and dyeing the material which remains, a first segmented filter is formed. The procedure is then twice repeated with the support being held in a different attitude with respect to the exposing radiation source in each instance so that the lenticules focus the radiation in laterally displaced regions of the opposite surface. By using different additive primary dyes in each dyeing step, three segmented interlaid filters can be produced.